1. Field of the Invention
The present invention relates to a riding-type working machine such as a riding-type lawn mower, for example.
2. Description of the Prior Art
Riding-type working machines such as riding-type lawn mowers generally have a radiator and a cooling fan which are positioned in front of the engine mounted in a front portion of the machine frame.
In order to prevent hot air from flowing toward the driver's seat, a radiator and a cooling fan may be positioned behind the engine so that the engine and the radiator will be forcibly cooled by air that is introduced from the side of the driver's seat.
A steering column is vertically disposed in front of the driver's seat centrally in the transverse direction of the machine frame, the steering column being usually in the shape of a truncated cone. To introduce a large amount of cooling air, the radiator and the cooling fan are sufficiently spaced from the steering column in front thereof, or are positioned laterally of the steering column.
With the radiator and the cooling fan positioned in front of the steering column in spaced relationship, an engine compartment defined by the engine hood is too long forwardly, making it difficult for the driver to have good front visibility and to make smaller turns, and also join various other working machines to the front end of the machine frame.
The radiator and the cooling fan which are positioned laterally of the steering column increase the width of the engine hood, affecting visibility of the front wheels and surroundings thereof, so that the driver may not efficiently work with the machine.
One conventional riding-type working machine has a steering gearbox mounted on the machine frame and a steering column mounted on the steering gearbox. Since the steering gearbox is coupled to the machine frame by bolts and nuts and the steering column is also coupled to the steering gearbox by bolts and nuts, many fastening elements, i.e., bolts and nuts, are required and the process of coupling those components is complex. Inasmuch as the steering gearbox is in the form of a casting, the bolts tend to work loose because of the difference in hardness between the steering gearbox and the machine frame and the steering column which are typically made of sheet steel. Another problem is that large loads applied from the steering handle may be transmitted through the steering column to the steering gearbox.